'I am writing to express grave concern over your administrations policy permitting the execution of American citizens suspected of affiliation with terrorist organizations.

'This appears to represent a disturbing violation of the Fifth Amendment of the United States Constitution which guarantees all American citizens due process under the law and protects individuals against government overreach.

'Your policy, which was conducted secretly until exposed by the media, also represents an outrageous circumvention of congressional oversight. According to press reports, the Democratic Chairman of the Senate Judiciary Committee, Patrick Leahy, and some of his Senate colleagues have been denied information about this policy when they requested details on 12 separate occasions.

'The secrecy behind this policy contradicts the remarks you made in a 2009 speech when you stated, Whenever we cannot release certain information to the public for valid national security reasons, I will insist that there is oversight of my actions -- by Congress or by the courts.

'Although national security is one of the most fundamental responsibilities of government, it should never come at the expense of the freedoms specifically enumerated in the Constitution. The U.S. Supreme Court, in Hamdi v. Rumsfeld, said, "A state of war is not a blank check for the president when it comes to the rights of the nation's citizens."

'Our country was founded on a system of checks and balances to protect the American people, yet your policy as put forth by the attorney general sets a dangerous precedent.

'No individual not the president, attorney general or a CIA operative should preside as judge, jury and executioner over the life of another American citizen. Even the Magna Carta, written 800 years ago, established the concept of due process, stating that no free man could be punished except through the law of the land.

'It is imperative that you explain to the American people why you believe the assassination of American citizens by their own government without due process is legally and constitutionally acceptable.